Idler wheel adjustment means



June 2 1942- J. s. HEAsLET IDLER WHEEL ADJUSTMENT MEANS 's sheets-smet 1 Filed sept. so, 1940 INVENToR James G Haas let BY Z f l ATTO RWM,

Juhe a, 1942-.` y J. G. AEASLET' 2,284,821

IDLER WHEEL ADJUSTMENT MEANS w Filed Sept. so, 1940 3 sheets-sheet 2 INVENToR James a. Heasut F ..5 'i5 gg xva. ...u

ATTORNEY 3 Sheets-Sheet 3 lNvENToR Ja' s mi "5% y (fw ATTORNEY Patented .lune 2, 1942 IDLER WHEEL DJUSTMENTjMEANS.

v James G. Heaslet, Hudson, Ohio, assignor to The Cleveland Tractor Company, Cleveland, Ohio Application september 30, 1940, serial No. 359,125 2 Claims. V(Cl. 305-9) This invention relates to .crawler type tractors and,more particularly, to a mechanism for adjusting the relative position of the front idler wheels over whichthe track chains pass when power is applied to the rear drivesprockets.

In tractors ci the type utilizing endless driven chains, it is customary to provide oiset pivoted frames on either side of the tractor chassis with front idler wheels mounted at the forward end of the side frames. Power driven sprocket wheels are positioned atthe rear sides of the chassis Y directly behind the pivoted side frameswith articulated chains composed of linked shoes encircling the idlers, frames and sprockets. ries of rollers are bearinged in the lower edge `of the side frames for supporting the weight of the tractor on the lower runrof the track chains, while one or more similar rollers on the top edge prevent the chains from sagging.

From this description of thedrive mechanism, it will be apparent to those skilled in the art that it is essential that the chains be kept in taut adjustment to insure that the full torque of the power plant is times. g

It has been proposed to mount the front idler wheels on movable bearings, to secure them to springs andthe like, and in other ways to compensate for wear and stretch of the chains. However, these prior devices have only been partially successful and it is, therefore, the prime object of the invention to construct the tractor side frames and idler wheel mountings in such a manner that the wheels may be readily adjusted to keep the desired tension on the chains and also to resiliently support the idler wheels so that they may withstand the shock of starting and stopping the chains and the stresses Fig. is a 'bottom plan of the removable coverv through which adjustment is secured; Y

Fig. 6 is arpartial vertical section taken on applied to the chains at all Ase- - having extension shafts 33.

line 3-3 of Fig. 1 showing the placement of the adjusting crank;

Fig. 7 is avertical section taken on line 'I-l of Fig. 1; and

Fig. 8 is a partial vertical section taken on line 8-8 of Fig. 1.

The general layout of the crawler type tractor side frame, including the present improvement for mounting and adjusting the front idler wheel, is shown in Fig. `1. In this view, the numeral I denotes an open bottom tubular side frame, pivotally mounted on laterally extending shaft 2 secured to the tractor chassis frame. The side frame I is preferably fabricated from a pair of plates 3-3, reinforced by additional interior plates 4-4, which are spaced from the depending sides of outer plates 3-,3. These series of plates are welded together in spaced relation, as

` shown in Figs. 3 and 7, with the upper meeting edges of plates 3-3 joined at 5. I A plurality of rollers I-B are journalled inbearings 1 1 along the lower. edges of the side frame plates 3 and 4 for the purpose of supporting the weight of the tractor on the lower run Yof the articulated chain I0. A top roller 8 is mounted on the upperpart of the frame 3 to support the upper flight of vthe chain which is driven :by rear sprocket wheel 9.

Within the connes of the inner plates 4 4, there is mounted a longitudinal cylinder I5 which is rigidly secured thereto'by a plurality of radial or transverse plates' I6. These plates I6 are weldedto the cylinder I5 and are provided withpairs of spaced laterally extending ears I1 that pass outwardly through registering openings I8 formed in the spaced parallel side plates 3 and 4. The upper parts of the plates l I6 are cut away and tted in slots I9 formed on the inner sides of the apex 5 of plates 3"3. These two forms of fastenings insure the rigidity of the cylinder.

Immediately behind the cylinder there is mounted a bracket 20 that is bolted to the side plates 3 and 4 by bolts 2|, which pass through the plates and spacer 22. The bracket 20 carries an arch member 23 joining the side portions 24 and also a longitudinal cylindrical sleeve or bushing 25 that is aligned with the center of the cylinder l5. An internally threadedV gear 30, having an integral offset flange 3l is carried in the bushing 25 and meshes with a worm 32 The extensions 33 are set in bearings 34 formed in the upper part of the arch member 23 and are secured thereinl by a complementary cap 35 bolted to the arch.

, tened to the screw 4I.

As shown in Figs. 2, 3, and 6, registering openings 36 are cut through the outer side plates 3 v means of a cover plate 42 and held in position by machine screws 43, while the underside of the cover plate is provided with a bifurcated prong 44 that is adapted to engage the shaft pin 38 and prevent movement thereof.

Referring now to the front idler wheel 45, it will be seen that it is mounted on an axle 45 whose ends are bolted through the sides of a sliding yoke 41 that rides on the top surfaces of the reduced height forward portion 48 of the side frames. The lower edges 49 of the yoke engage bars 5U to hold the idler wheel assembly in place.

At the'rear of the yoke 41, the arms thereof are brought together and fastened to a long bolt 5I which extends rearwardly into the cylinder I5 and terminates within a tting 52 that is fas- The fitting 52 is ilanged and bolted to a collar 53 encircling the nut end of bolt 5I. A similar collar 54 is ntted on the opposite end of the bolt and rests against the yoke and bolt fastening. Two coiled springs are concentrically arranged around the bolt 5l, the inner spring 51 being tensioned between the inner ends of the collars 53 and 54, While the larger and strong spring 58 is precompressed between the flange portions of the collars. Adjustment of the proper degree of compression is secured by rotation of the nut 59 on bolt 5I. This arrangement allows a certain amount of shock absorption to take place when the chains strike an obstacle and when applying power to the chassis without being transmitted to the tractor chassis.

As wear occurs to the articulated chain or when relative looseness or tightness is desired, the front idler may be accurately and easily adjusted by removing the cover plate 42 and engaging the worm 33 by the crank 4U. Operation of thecrank 43 allows the operator to move the idler wheel assembly either backward or forward to secure the precise adjustment neededfor the particular work involved. After adjustment, the replacing of the cover cap 42 and yoke 44 locks the parts in position and prevents them from moving.

What I claim is:

1. A side frame for crawler tractors comprising an elongated open bottom, box-like member Whose sides are reduced in height and extend beyond the box-like portion, a slidable carrier adapted to ride on the said extended sides, an axle secured to said carrier, an idler wheel thereon, and means carried interiorly of said box-like member for adjusting the relative position of said carrier on said extended sides, said means including a rearwardly` extending shock-absorbing spring device fastened to said carrier, a screwthreaded bar fastened to the opposite end of said spring device, said bar being threaded through a gear having an internally threaded hub and a worm gear mounted at right angles to and meshing with said gear, said worm gear being adapted to be rotated to move said carrier by a hand crank inserted through an opening in said box-like member, said opening having a cover plate provided with a prong on its underside to engage said worm and prevent its rotation when said cover plate is in closed position.

2. A side frame construction for crawler type tractors comprising an elongated open bottom hollow member pivotally secured to the frame of the tractor, weight supporting rollers mounted on the lower edges of said hollow member, and a chain supporting roller on the top of said hollow member, said hollow member having its forward portion reduced in height to provide spaced guides for an idler Wheel bearinged in a sliding carrier and mounted on said forward reduced portion, a longitudinal cylinder secured within said elongated hollow member, said cylinder having a plurality of radial flanges fastened to the interior walls of said hollow member, a bracket secured to the side walls of the hollow member adjacent the rear end of said cylinder, said bracket carrying a longitudinal internally threaded bushing having a transverse external gear. on one end thereof, a worm gear bearinged in said bracket and meshing with said external gear, a rod threaded through said bushing and extending into said cylinder, and an intermediate spring device secured to said rod and said sliding carrier, the intermediate spring device lying substantially within said cylinder, said carrier being movable upon rotation of said worm gear.

JAMES G. HEASLET. 

